Apparatus and method for providing constant-heat, variable-pattern burner flame



Nov. 16, 1965 T. s. VOORHEIS APPARATUS AND METHOD FOR PROVIDING CONSTANT-HEAT, VARIABLE-PATTERN BURNER FLAME Filed Dec. 16, 1965 INVENTOR. Temple 8. Voorheis 3,218,049 APPARATUS AND METHOD FOR PROVIDING CONSTANT-HEAT, VARIABLE-PATTERN BURN- ER FLAME Temple S. Voorheis, Paio Alto, Calif., assignor to Coen Company, Inc., San Francisco, Calif, a corporation of California Filed Dec. 16, 1963, Ser. No. 330,952 10 Claims. (Cl. 26333) This invention relates to a burner nozzle and accouterments therefor for providing a burner flame of variable pattern and constant rate of heat energy output, and to a method for producing a flame having the enumerated characteristics. Although the description of the invention herein relates to a burner for a rotary kiln, the invention is not to be considered as limited to such device but has equal application in any system wherein a variable flame pattern, with constant heat energy for all variations in flame pattern, is necessary.

A typical rotary kiln includes an elongate rotatable chamber which is slightly sloped from horizontal and wherein the raw materials are fed into the higher end. An axial burner is typically provided in the lower end of the kiln, the raw materials gravitating toward the burner nozzle in response to rotation of the kiln. Variation in operating parameters is necessary for processing raw materials of varying composition and for securing a desired end product. Included among the variable parameters are flame shape and heat energy input to the kiln. Typically, the rate of heat energy input to the kiln is selected at the outset, and during kiln operation, the flame pattern is adjusted to establish the proper operating conditions. During adjustment of the flame pattern it is desirable to maintain constant the rate of heat energy input to secure a consistent product.

Recent developments in improving rotary kiln efficiency have resulted in a reduction of the inflow rate of relatively cool combustion air (primary air) with a concurrent increase in preheated air (secondary air), such as from a clinker cooler. Prior art techniques for varying the flame pattern by varying the rate of primary air inflow are thus becoming obsolete.

In the present invention a burner nozzle having axially directed fuel jet openings and outwardly directed fuel jet openings is disposed in the stream of primary air inflow. Since the rate of primary air inflow in minimal and not variable within a suflicient range to alter effectively the flame pattern, the rate of fuel flow from either the axial jet openings or the outwardly directed jet openings is throttled. Such throttling effects a change in flame pattern by reducing one of the components of fuel inflow. Throttling of only one of the components however alters the fuel pressure at the nozzle and would, without compensation, alter the rate of heat energy input to the kiln.

Therefore, it is an object of the present invention to provide apparatus for producing a burner flame of variable flame pattern while maintaining constant the rate of heat energy produced by the flame. This object is achieved by providing apparatus for delivering a constant flow of fuel to the burner nozzle irrespective of the size of the jet openings in the nozzle. Such apparatus basically includes an orifice in the fuel line feeding the nozzle and facilities for maintaining the pressure differential across the orifice at a fixed magnitude.

Another object is to provide apparatus of the type described above in which the rate of heat produced by the burner can be adjusted to a preselected value and then the flame pattern can be altered while the preselected value of heat input is maintained. This object is nited States Patent 3,Zi8,fl49 Patented Nov. 16, 1965 achieved by the present invention in one of two ways, the first of which is providing an orifice in the fuel line that is adjustable in size in accordance with the heat inflow desired and maintaining the pressure across the orifice constant for all flame patterns. The second way of achieving the object is by providing a fixed orifice in the fuel line and then maintaining a preselected differential pressure across the orifice of a magnitude that will produce the desired rate of heat input. The preselected differential pressure is maintained constant as the flame pattern is varied.

Still another object is to provide a burner nozzle having an axially directed fuel opening which fuel opening can be varied in size to throttle the rate of fuel inflow and to provide in combination with the nozzle apparatus for conveying to the nozzle a constant flow of fuel irrespective of the size of the opening. In the preferred embodiment of the present invention the nozzle fuel opening is provided by a generally frusto-conical flange in which a tapered plug is reciprocally movable between a full closed position and an opened position. In closed position the burner offers more resistance to fuel flow and hence causes the pressure behind the burner nozzle to increase. Apparatus is provided for increasing the pressure of the fuel delivered to the nozzle to compensate for the above described phenonemon.

Yet another object is to provide a method for maintaining constant the heat energy produced by a burner and for varying the pattern of the flame produced while maintaining constant the rate of heat produced.

These and other objects will be more apparent after referring to the following specification and accompanying drawings in which:

FIGURE 1 is a schematic view of the preferred embodiment of the present burner control system with a rotary kiln shown fragmentarily;

FIGURE 2 is a cross-sectional view of a burner nozzle in an open position whereby a long flame pattern is produced;

FIGURE 3 is a cross-sectional view of a burner nozzle in a closed position whereby a short bushy flame is produced; and

FIGURE 4 is a schematic view of an alternate embodiment of apparatus for controlling the fuel flow to the burner nozzle.

A typical kiln includes an elongate rotatable sloped heating chamber C, the lower end of which i housed in a hood H. The hood defines a duct D for conveying preheated secondary air to chamber C, such conveyance being along a path designated at S. Extending through hood H into chamber C is a 'burner designated generally at 12 which burner includes an outer housing 14 for defining a passageway for primary air. Primary air is fed along a path indicated at P from a conventional fan or the like (not shown). Disposed within housing 14 and concentric therewith is a gas tube 16 fed by a fuel line 18.

Tube 16 terminates within chamber C at a nozzle designated generally at 20. Nozzle 20 includes an annular plate 22 having outwardly directed fuel jet opening 24 therein. Tube 16, somewhat behind annular plate 22, is provided with additional outwardly directed fuel jet openings 26; the angle at which jet openings 24 and 25 are oriented relative to the axis of burner 12 is chosen according to the kiln size and other similar limitations, and is well within the competence of those skilled in the art. Extending rearwardly from the opening of annular plate 22 is an outwardly extending flange 28, the interior surface of which defines a generally frusto-conical surface. Disposed coaxially with flange 28 is a reciprocal adjusting member 30 which extends rearwardly of the burner and is fitted with an adjusting device 32 which can take any suitable form, for example, a threaded shaft engaged in a threaded opening. Although member 36} is shown as a hollow tube, such form is not mandatory in the present invention.

Referring to FIGURE 2, nozzle 20 is shown in a position wherein a long, narrow fiame pattern i produced thereby. A plug 3-} is secured to the inner end of member 30 and has a peripheral surface 36 complementary with inner surface of flange 28 so that in the forwardmost position of plug 34, no opening EXlSIS between the periphery of the plug and the inner surface of the flange. In the position of plug 34-, as depicted in FIGURE 2, gas emanating'from nozzle 2t) will move in a predominantly axial direction as a consequence of which the flame pattern will be long, narrow and extending well into kiln chamber C. Adjustment of control 32 to move plug 34 to the closed position, as shown in FIGURE 3, reduces the axial component of gas fiow emanating from nozzle 20. Therefore, the gas flowing from jet openings 24 and 26 predominates to form a short bushy fiame pattern.

Since the total area of opening in nozzle 20 varies as plug 34 is moved between the extreme positions thereof, a varying resistance to gas flow is established. Apparatus for compensating for this condition is provided in fuel line 13. A conventional diaphragm motor flow control valve 33 (FIGURE 1) is provided in fuel line 13 and has an operating rod so, the axial position of which determines the size of the opening through the valve. Upstream of valve 38 is a second valve 42, also a conventional device, such as that shown in U.S. Patent No. 2,315,171. Valve 42 has a lever 4-4 for controlling the orifice opening within the latter valve. A differential pressure controller 46 is operatively connected to rod 44 and senses the pressure on the down stream side of valve 42 through a line as and the pressure on the upstream side of valve 42 through a line 5t}. Differential pressure controller 46 is any one of a number of conventional devices, for example, a device having a diaphragm on opposite sides of which lin s 48 and 5t? communicate. The distension of the diaphragm is proportional to the pressure difference sensed at lines 48 and 59. Therefore, when an increase in pressure differential between lines 4% and 5% is sensed in controller 46, the controller acts through rod 49 on valve 38 to close valve 38 thereby reducing the fiow through line 18. An increase in pressure differential across valve 42 would occur when nozzle plug 34- was moved to the open position causing the flow rate of the gas emanating from the nozzle to increase. Oppositely, when a decrease in differential pressure between lines 48 and St is sensed, controller as acts to open valve 33 thereby to increase the flow, and hence, to restore the preset pressure differential.

Linked to lever 44 of valve 42 is a conventional actuator 52 which is used to position valve 42 from a remote site in order that the total heat energy input to the system can be modified from a remote burner control panel.

The operation of the embodiment of the present invention shown in FIGURE 1 is as follows: with gas flowing through valves 42 and 38 in line 18 and into nozzle 20, the desired heat energy input to the kiln i adjusted by adjusting actuator 52. In typical kiln operation the rate of heat energy input to the kiln needs adjustment only infrequently, and for purposes of the present description can be considered constant. The burnerman can now secure the optimum flame pattern by adjustment of control 32 which moves plug 34 within flange 28. Should a long flame pattern be desired, controller 32 is moved to position plug 34 as shown in FIGURE 2. At such position, the resistance to flow offered by nozzle 20 is relatively slight, and therefore sufiicient gas to provide the required heat input can be fed to the kiln at a relatively low pressure. In such position, valve 38 is in a relatively closed position and will, through the action of pressure controller 46, maintain a constant differential across the orifice of valve 42. Since the size of the latter orifice is constant, a constant rate of gas flow will enter nozzle Ztl, as a consequence of which the heat input to the kiln will remain constant. Should itsubsequently become necessary to alter the flame pattern and move it toward a short, bushy pattern, controller 32 is operated to move plug 34 forwardly in fiange 28, thus to close the spacing between periphery 36 of the plug and the frustoconical interior surface of flange 28. FIGURE 3 depicts the full closed position of nozzle 2%. In such position the nozzle presents a relatively high resistance to gas flow through the nozzle which resistance decreases the gas flow through the orifice of valve 42. Upon decrease of the flow through valve 42 a change in differential pressure between lines 48 and 5-9 is sensed, and controller 4-6 opens valve 38. Such action increases the flow of gas through the line and through nozzle 20, thereby maintaining constant the rate of heat energy flow to the kiln. Such regulating operation continues as the size of the opening in nozzle 20 is adjusted for changing flame patterns in FIGURE 4, a modification of the present invention is shown schematically. Upstream of valve 323 in line 13 is a fixed orifice 42 having a pressure line 48 on the downstream side thereof and a pressure line 5%) on the upstream side thereof. Lines 48 and 5h communicate the pressure on opposite sides of orifice all to a differential pressure controller 46 which is substantially similar to controller 46 described hereinabove. Associated with controller 4-6 is a remote manually controllable air pressure source 56. Fressure source 56 acts through a conventional diaphragm control motor 58 to preset dilferential pressure controller 46' so that the controller maintains a preselected but variable differential pressure between lines 48' and 5t).

The'operation of this modification of my invention is as follows: The rate of heat energy input to the kiln is adjusted by adjusting the pressure of the air supplied by source 56 to diaphragm motor 5%. Such adjustment preloads the diaphragm within controller 46' to the end that the difierential pressure sensed across lines 48 and 5G is prebiased in accordance with the air pressure supplied from source 56. Source 56 thus affords adjustment of the rate of gas flow to nozzle 2h. When a correct rate of heat inflow has been selected, the system operation is similar to that of the embodiment to FIGURE 1. As the flame pattern is altered by movement of plug 34 within flange 23, difierential pressure across orifice 42' activates controller 46 to move valve 38 so as to compensate for the pressure changes and restore the differential across fixed orifice 42' to the preset value. Of course, constant differential pressure across the fixed orifice establishes the rate of flow of gas through the line 13 at the fixed value, as a consequence of which the rate of heat infiow into the kiln is maintained constant for all flame patterns produced by the nozzle.

Thus, I have provided an apparatus and method for maintaining a constant rate of heat production from a flame that is capable of various shapes. By use of the present invention one operating parameter, flame pattern, can be varied without altering any other parameters, e.g., rate of thermal input to the system.

While two embodiments of my invention have been shown and described, it will be obvious that other adaptations and modifications may be made without departing from the true spirit and scope of the invention.

What is claimed is:

l. In combination with a burner nozzle of the type that is adjustable to alter the flame pattern produced by the nozzle and is supplied with fuel through a line, apparatus for maintaining constant the rate of fuel flow to the nozzle for all flame pattern adjustments thereof comprising means defining an orifice in said fuel line, means for measuring fuel pressure on the upstream side of said orifice, means for measuring fuel pressure on the downstream side of said orifice, means for regulating the rate of fuel liow through said line downstream of said orifice,

and means responsive to said measuring means for controlling said regulating means to maintain a constant differential pressure between the upstream and downstream sides of said orifice for all flame pattern adjustments of said nozzle, whereby the rate of heat energy produced by said nozzle is maintained constant for all flame patterns produced by said nozzle.

'2. In combination with a burner nozzle having fixed axially and radially directed jet openings and a generally axially directed annular opening adjustable for varying the pattern of the flame produced by said nozzle, said nozzle being fed by a fuel line, apparatus for controlling the rate of fuel flow to said burner nozzle comprising means for defining an adjustable orifice in said fuel line, means for measuring the pressure differential across said orifice, means for controlling the rate of fuel flow through said line, means responsive to said pressure differential measuring means for regulating said controlling means to maintain constant the pressure diflerential across said orifice, thereby to maintain constant the rate of fuel flow to said nozzle for all flame pattern adjusments thereof, whereby the rate of fuel flow to said nozzle can be varied by adjusting said orifice and the rate can be maintained constant for all flame patterns produced by said nozzle by maintaining constant the pressure differential across said orifice.

3. In combination with a burner nozzle having fixed axially and radially directed jet openings and a generally axially directed annular opening adjustable for varying the pattern of the flame produced by said nozzle, said nozzle being fed by a fuel line, apparatus for controlling the rate of fuel flow to said burner nozzle comprising means defining an orifice in said fuel line, means for measuring fuel pressure on the upstream side of said orifice, means for measuring fuel pressure on the downstream side of said orifice, means for regulating the rate of fuel flow through said line downstream of said orifice, and means responsive to said measuring means for controlling said regulating means to maintain a preselected differential pressure across said orifice, said controlling means being adjustable so that the heat energy produced by said nozzle can be established at a preselected rate and there maintained constant by said controlling means.

4. A kiln burner for a rotary kiln comprising means defining an air passage into said kiln axially thereof, a tube in said air passage disposed axially thereof for conveying gas thereto, a nozzle including an annular plate secured to the end of said tube and formed with a plurality of outwardly directed gas jet openings, said annular plate having a circular opening therein, a flange secured around said opening and extending rearwardly and outwardly thereof, a plug reciprocally movable within said flange between a forward closed position and a rearward open position, whereby the axial component of gas flow into said kiln can be altered by moving said plug thereby to alter the flame pattern produced by said nozzle, a fuel line for feeding fuel to said tube, an orifice in said fuel line, means for measuring fuel pressure on the upstream side of said orifice, means for measuring fuel pressure on the downstream side of said orifice, means for regulating the rate of fuel flow through said line downstream of said orifice, and means responsive to said measuring means for controlling and regulating means to maintain a constant differential pressure between the upstream and downstream sides of said orifice, whereby the rate for heat energy input to said kiln is maintained constant for all flame patterns produced by said nozzle.

5. In a rotary kiln having a nozzle for firing the kiln from one end thereof, the nozzle being adjustable for varying flame pattern in the kiln and being fed by a fuel line, a method for maintaining constant the heat input to the kiln for various flame patterns comprising the steps of providing an orifice in the fuel line, providing a valve in the fuel line for controlling the rate of flow therethrough and adjusting said valve to maintain a constant pressure differential across said orifice for all flame pattern adjustments of the nozzle.

6. A method for varying the flame pattern in a rotary kiln and simultaneously maintaining constant the rate of heat energy input to the kiln comprising the steps of providing a nozzle having a fuel jet opening directed axially of the kiln and a fuel jet opening directed outwardly from an axial direction, supplying fuel to the nozzle through an orifice, varying the flame pattern produced by the nozzle by altering the size of at least one of the fuel jet openings, providing a fuel flow regulating valve between the nozzle and the orifice, and adjusting the regulating valve to maintain constant fuel pressure differential across the orifice.

7. The method of claim 6 including the step of controllably varying the size of the orifice to adjust the rate of heat energy input to the kiln.

8. The method of claim 6 including the step of controllably varying the constant fuel pressure differential maintained across the orifice to adjust the rate of heat energy input to the kiln.

9. The method of maintaining constant the rate of heat energy input to a kiln of the type having a burner nozzle with axially directed fuel jets, outwardly directed fuel jets, and means for throttling the flow of fuel from one of said jets to alter the flame pattern produced by the nozzle, which method comprises the steps of feeding fuel to the nozzle through a line that includes an orifice and a regulating valve, measuring the pressure differential across orifice, and adjusting the regulating valve to maintain constant the pressure differential across the orifice for all settings of the fuel flow throttling means, whereby the rate of heat energy input to kiln is maintained constant for all flame patterns produced by the nozzle.

10. A method for varying the flame pattern in a rotary kiln and simultaneously maintaining constant the rate of heat energy input to the kiln comprising the steps of providing a nozzle having a fuel jet opening directed axially of the kiln and a fuel jet opening directed outwardly from an axial direction, supplying fuel to the nozzle through an orifice, varying the flame pattern produced by the nozzle by altering the size of at least one of the fuel jet openings, maintaining constant the fuel pressure differential across said orifice.

References Cited by the Examiner UNITED STATES PATENTS 2,776,827 1/1957 Graham 263-52 2,857,148 10/1958 Niernitz 26333 CHARLES SUKALO, Primary Examiner.

JOHN J. CAMBY, Examiner. 

5. IN A ROTARY KILN HAVING A NOZZLE FOR FIRING THE KILN FROM ONE END THEREOF, THE NOZZLE BEING ADJUSTABLE FOR VARYING FLAME PATTERN IN THE KILN AND BEING FED BY A FUEL LINE, A METHOD FOR MAINTAINING CONSTANT THE HEAT INPUT TO THE KILN FOR VARIOUS FLAME PATTERNS COMPRISING THE STEPS OF PROVIDING AN ORIFICE IN THE FUEL LINE, PROVIDING A VALVE IN THE FUEL LINE FOR CONTROLLING THE RATE OF FLOW THERETHROUGH AND ADJUSTING SAID VALVE TO MAINTAIN A CONSTANT PRESSURE DIFFERENTIAL ACROSS SAID ORIFICE FOR ALL FLAME PATTERN ADJUSTMENTS OF THE NOZZLE. 